Recycle bin & export data mismatch

Question

Hi All,
Please find the below for your reference and schema test size shows 70gb while query in dba_segments and it show 32gb when i exclude the segments from recycle bin.
What is the exact size of this test schema? Why the size difference? How to avoid this ?
SQL> select sum(bytes)/1024/1024/1024 from dba_segments where owner='TEST' ;
SUM(BYTES)/1024/1024/1024
70.9247437
SQL> select sum(bytes)/1024/1024/1024 from dba_segments where owner='TEST' and segment_name not like 'BIN%';
SUM(BYTES)/1024/1024/1024
32.9226685
Thanks

Answer 1

Hi,
actually when you drop a table with 5GB for example (drop table test;),
oracle actually rename the table test to something BIN********, to allow you to undrop it if you want using the following statement:
SQL> flashback table test to before drop;
and you can show these BIN***** tables using the following command:
SQL>show recyclebin;
and you can select from them using the following query:
select * from "BIN******";
but oracle will release the space (drop it permanently) for these BIN**** tables ( droped tables) in some cases, the following some of them:
1. when you drop a table with purge option:
drop table test purge.
2. when you purge the recyclebin:
SQL>purge recyclebin;
3. when the tablespace become under presssure size.
regards,
Tareq Alkhateeb